1. Field of the Invention
The present invention relates to a pulse combustion device, and more particularly to a pulse combustion device adapted for use in a liquid heating apparatus such as a water heater of the storage type, a deep fat flyer or the like.
2. Description of the Prior Art
In Japanese Patent Early Publication No. 55-102804, there has been proposed a pulse combustion device adapted for use in a heat preserving boiler, wherein a combustion chamber is mounted within an upper portion of an upright closed water vessel, and wherein a plurality of spiral tailpipes are connected to the combustion chamber and extended downwardly to heat the water stored in the vessel. The tailpipes are further extended outwardly from a bottom portion of the vessel in a liquid-tight manner. Since the pulse combustion device has to be fixedly mounted to the upper and bottom portions of the vessel, plenty of time is consumed for mounting and removal of the combustion device to and from the vessel. In application of the pulse combustion device to the heat preserving boiler, scale containing various salt of calcium, magnesium and the like and hydrooxide adhered to the tailpipes falls and precipitates on the bottom of the water vessel. If the tailpipes are partly covered with such precipitated scale, heat transfer of the tailpipes will be deteriorated to cause overheat of the tailpipes and cracks in the welded portions of the combustion device. If the precipitated scale is not removed from the water vessel because of the difficulty in removal of the combustion device, the above problems will occur. In the case that the pulse combustion device is arranged in the upper portion of the water vessel to avoid the problems, the temperature of hot water discharged from the vessel in continuous use will drop immediately due to the cold water in the lower portion of the vessel.